Influence of proximal box elevation on bond strength of composite inlays

The objective of the present study was to evaluate the influence of proximal box elevation on microtensile bond strength (mTBS) of composite inlays to the proximal box floor, using either a total-etch or a self-adhesive resin cement.

Twenty-five human molars were selected, and a class II OM (inlay) cavity preparation was performed in each tooth. Cavities were randomly assigned into four experimental groups, according to the location of the proximal cervical margin (located 1 mm below cementoenamel junction (CEJ), or with proximal box elevation with composite resin) and the resin cement used for luting (a total-etch resin cement RelyX ARC or a self-adhesive resin cement G-Cem). After 1-week water storage, samples were subjected to mTBS test. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05).

Kruskal-Wallis revealed statistically significant differences among experimental groups (p = 0.007). Both resin cements showed similar bond strength values when cervical margin was located below CEJ. The proximal box elevation improved the bond strength of composite inlays for both resin cements. However, only for G-Cem was this improvement statistically significant.

The proximal box elevation improved the bond strength attained by G-Cem resin cement. For RelyX ARC, the position of the cervical margin did not affect composite inlays bond strength.

Proximal box elevation does not decline bond strength of composite inlays to the proximal floor when a total-etch or a self-adhesive resin cement is used.